%0 Journal Article
%A Oñate, J. I.
%A García, A.
%A Bellido, V.
%A Viviente, J. L.
%T Deposition of hydrogenated B-C thin films and their mechanical and chemical characterization
%D 1991
%@ 0257-8972
%U https://hdl.handle.net/11556/4370
%X Considerable interest has arisen during the last decade on the deposition of diamond and diamond-like films because of their unique properties which suggest a range of applications. This paper reports on the r.f. plasma chemical vapour deposition of hydrogenated B-C films and evaluation of their mechanical and chemical properties. Thin films were deposited using various ratios of 5 vol.% B2H6 in H2 and CH4, while varying the substrate temperature, total gas pressure and r.f. power. It is shown that high B2H6-to-CH4 ratios can lead to deposition of very hard thin films. An ultramicrohardness technique, measuring hardness under loading, has been used within a load range 0.4-25.6 mN, in order to limit the penetration of the indenter. This testing approach shows hardness values of approximately three times that of a hardened and tempered AISI M2 high speed steel substrate. The films also exhibit an elastic behaviour, compared with the more plastic behaviour of the substrate material. Scratch adhesion testing shows maximum values for a critical load of approximately 20 N for 0.2 μm films on steel substrates. Thicker films exhibit lower adhesion values owing to the high stresses of the films. Adhesion of films deposited on Al2O3 substrates is higher and flaking is significantly reduced at high loads. IR spectra show that these films have significant B-C, B-H and C-H bonds. XPS data also demonstrate that carbidic bonds are present in C 1s and B 1s spectra; this jointly with the high stresses of films can explain the hardness values obtained.
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